Pipette pump



NOV. 22, 1960 G 5, PRICE 2,960,868

PIPETTE PUMP Filed Dec. 25, 1957 GEORGE E. PRICE INVENTOR.

can be drawn up into the pipette.

United States Patent PIPETTE PUMP George E. Price, 5013 E. 13th St, Des Moines, Iowa Filed Dec. 23, 1957, Ser. No. 704,574

1 Claim. ((31. 73-.,425.6)

This present invention relates to the general art of .pipettes such as are generally used in the handling of relatively small quantities of liquids. More specifically this invention relates to a pipette which is provided with a relatively simple means for drawing liquids up into the pipette assembly or discharging the same through the employment of two closely spaced rollers which engage a rubbertube secured to a standard pipette in a manner to ,fully compress the tube. As the rollers are moved along the tube they will either draw liquid up into the pipette and into the tube if the movement is continued far enough or in a reverse manner as the rollers are moved down toward the liquid it will discharge the liquid previously drawn into the pipette. To provide a delicate adjustment or more properly a Vernier control of the movement of the liquid either into or out of the pipette, the rollers may be turned by means of a hand wheel so that a precise control is provided for the device.

Pipettes of the type made of glass so that they are transparent and graduated so that quantities can be determined have long been used in the transfer of small quantities of liquids, particularly in laboratories and the like. In its simplest form a pipette of course consists of an elongated glass member, one end of which is taken between the lips of the user and by mouth suction the liquid Discharge can be efi ected by applying mouth pressure or where the diameter of the pipette is sufficient or the head of liquid sufficient gravity can be relied upon for the discharge. The former mode of handling the pipette is often very dangerous to the operator as some of the liquid may be taken into the mouth. Further accurate control of the liquid dispensed is difiicult and therefore this inaccurate manned of handling liquids is seldom attempted in precise work.

In this present invention means are employed to use a rubber tube extension on a glass pipette and to then provide mechanical means so that the pipette can be quickly filled or discharged or it may be by turning the rollers themselves, liquid may be discharged very s owly and carefully and in this manner the discharge is under very complete and precise control of the operator. A pipette of this order, which might more properly be called a pipette pump has been used in industry and in laboratories where chemical liquids harmful to the membranes of the mouth or even poisonous liquids can be easily and safely handled. In certain laboratory work it is very often necessary to handle contagious disease germs and the like and finally there are many forms of liquids such as radioactive isotopes which cannot be safely handled in the ordinary pipette. All these various conditions can be safely and quickly handled with this present device and where conditions warrant, very precise handling can be achieved.

The principal object of this present invention, therefore, is to provide a pipette pump in which two speeds are in effect provided. One speed permits the quick filling or emptying of the p pette and the slow speed permits very precfse handling of liquids.

Afurther object of this invention is to provide a pipette means in which various liquids harmful to the human body can be safely handled without endangering the health of the user.

A further object of this invention is to provide a pipette pump that can be most economically manufactured to the end that a large number of these units can be employed in any one facility such as a laboratory or hospital or the like so that pipettes may be readily available for various types of fluids and thus obviate the necessity of thorough cleaning of the same between each use on different liquids.

Further objects, advantages and capabilities will be apparent from the description and disclosure in the drawings, or may be comprehended or are inherent in the de vice.

In the drawings:

Figure l is a perspective view showing one form of this pipette pump and illustrating the manner in which it is normally used.

Figure 2 is a side elevation, partly in section 1 of a pipette pump similar in many respects to the one shown in Figure 1 but in which the bearings on the rubber tube are spread apart much further.

Figure 3 is a view, partly in section of a preferred form of the roller mechanism that is used generally in all forms of this pipette pump, the same being shown with a fiattened rubber tube between the rollers.

Figure 4 illustrates a very simple form of this pipette pump in which the rollers are disposed between the guide bearings which encircle the rubber tube.

Referring to the drawings, throughout which like reference numerals indicate like parts, the numeral 10 designates a conventional type of pipette usually provided with a graduated body so that exact measurements can be made and a pointed end 12 so that drops can be easily formed and thus provide for precise handling of liquids. At its upper end a pipette is usually provided with an enlarged portion as 14 so that a reserve of the liquid can be drawn up into the pipette and very substantially increase its capacity. Secured to the upper end of the pipette is a flexible hose 16. Rubber hose of the pure gum type is the most pliant and therefore one of the most satisfactory in use, however, there are a number of different materials out of which such suitable hose can be made.

To provide a means for stripping the hose and thus cause it to fill or discharge the pipette, the roller assembly shown in elevation in Figure 3 has proven satisfactory. This assembly consists of the two spaced rollers 20 and 22 which are disposed in spaced apart parallel relationship in frame 24. Frame 24 can be made of any suitable metal or plastic material that will give a rigid framework. Rollers 20 and 22, however, are preferably made from plastics of the general type of nylon because this material has a relatively high coefficient of friction when used in conjunction with rubber or rubber substitutes and thus provides for the easy movement of the roller assembly along the hose, as the rollers are revolved.

Each of the rollers 20 and 22 are provided with reduced diameter journals 26 and these journals are seated, for revolution, within the bearings 28 fixedly provided in frame 24. One of the rollers as 20, properly designated the driving roller has one of its journals extended at 30 so that an operating knob 32 can be disposed thereon and at a considerable distance from the rollers so that the thumb and fingers of the operator can easily turn the knob without interference from the roller mechanism assembly. For certain uses it is desirable to have a graduated dial as 34 and this is preferably secured to the opposite journal of the driving roller 20 so that the operator will have a positive indication of how much the roller is actually turned when effort is supplied.

l V 3 v A pipette pump of this general order has wide application and is used under varying conditions to handle also a wide range of liquids, consequently it is desirable to provide the roller assembly in a form that is best suited for the various uses and to this end three different species of the frame 24 have been shown in the drawings. Referring to the showing in Figure l a framework is provided in which hose guide caps as 40 and 42 encircle the hose and are slidable thereon, with one of the bearings disposed on each side of the rollers themselves. For use with various flasks used in chemical work, as that indicated at 48, a base is provided so that the pipette can in many instances be stood upright in the flask and in this manner avoid contamination. Under such conditions the form of framework shown in Figure l is very desirable.

In.this arrangement framework supporting bearings 44 and 46 are provided which also encircle the hose but these are secured to the hose preferably by having the bore of these hearings reduced sufliciently to snugly engage the members so as to space these two guides apart considerable, with the roller assembly disposed between these two bearings as will be noted in the figure. This form lends itself to very economical production in that the framework can best be made of two similar members 50 and 52 which are put together over the journals of the rollers and then secured in this assembled position by slipping guide caps 40 and 42 over the ends of the frame members so as to hold the two frame members in fixed relationship to each other.

Method of use The simplest form of quickly filling the pipette with liquid or discharging liquid therefrom is to move the roller assembly as a whole along by grasping the framework itself rather than directly turning the rollers. When this is done of course the hose 16 must be grasped in a manner to resist moving the pipette itself. Consequently, in filling the pipette the hose would be grasped near the pipette and the roller assembly frame moved bodily along the hose. Whendischarging the liquid thus drawn into the pipette the hose would need to be grasped on the opposite side of the frame from the pipette and then the roller assembly moved down towards the pipette in the discharging action.

To get the fullest use out of this equipment, however, it

should be used as a Vernier or precision type of pump and this is achieved by moving the rollers along the hose by turning operating knob 32 and thus turning roller 20,

Experience has shown that it is only necessary to turn one of the rollers if suitable materials are selected for their construction and this will cause the other roller as 22 to be properly revolved by frictional contact with the hose. Due to the fact that the rollers themselves are of relatively small diameter they move the roller framework along the hose very slowly and this makes it possible to discharge very small quantities of liquid very slowly if that is desired. This delicate adjustment of the position of the rollers gives a very accurate control of the pipettes functioning in that a very small amount of liquid can be taken out of a vessel or, on the other hand, a very small amount may be added to a vessel.

Quite often, a combination of these two methods of operating disclosed are employed, the stripping or moving the roller assembly by grasping the framework as it is moved along the hose will fill the hose most quickly and then the operating knob may be used to discharge, the liquid in as precise a manner as the circumstances require.

It is believed that it will be clearly apparent from the above description and the disclosure in the drawings that the invention comprehends a novel construction of a pipette pump.

Having thus disclosed the invention, I claim:

A pump means for use with pipettes to facilitate filling and discharging liquid therefrom, comprising: a framework having spaced and aligned framework supporting caps for snugly mounting on a hose; a flexible hose adapted to be operatively secured at one end to a pipette and having its other end engaged by said framework supporting caps; two parallel disposed rollers, providing a driving roller and a coacting driven roller of equal size, having reduced diameter journals revolvably positioned in fixed bearings in said framework; saidfixed, bearings adapted to position said rollers in a fixed plane and at a fixed distance apart, said rollers engaging said hose, on opposite sides and spaced apart sufliciently to flatten said hose and press the flattened interior wall into fluid tight engagement; extensions of the journals at both ends of the same roller; said driving roller having an operating knob on one extension for the purpose of manually turning said roller and a graduated dial on the other extension of said roller; said framework formed to two similar members which join on a plane through the axis of the hose and said hose guide caps adapted to fit over the opposite ends of the framework members and secure said members in position for use and to guide and position said hose for engagement with said rollers.

References Cited in the file of this patent UNITED STATES PATENTS 917,442 Hutchinson A s, 1909 1,098,514 Maddox June 2, 1914 2,094,524 Busch Sept.'28, 1937 FOREIGN PATENTS 310,020 Italy July22, 1933 

